7 DRUG INTERACTIONS
7.1 Drugs and Supplements Increasing Serum Potassium
Concomitant administration of ALDACTONE with potassium supplementation or drugs that can increase potassium may lead to severe hyperkalemia. In general, discontinue potassium supplementation in heart failure patients who start ALDACTONE [see Warnings and Precautions (5.1) and Clinical Pharmacology (12.3)]. Check serum potassium levels when ACE inhibitor or ARB therapy is altered in patients receiving ALDACTONE.
Examples of drugs that can increase potassium include:
- ACE inhibitors
- angiotensin receptor blockers
- non-steroidal anti-inflammatory drugs (NSAIDs)
- heparin and low molecular weight heparin
Like other diuretics, ALDACTONE reduces the renal clearance of lithium, thus increasing the risk of lithium toxicity. Monitor lithium levels periodically when ALDACTONE is coadministered [see Clinical Pharmacology (12.3)].
7.3 Nonsteroidal anti-inflammatory drugs (NSAIDs)
In some patients, the administration of an NSAID can reduce the diuretic, natriuretic, and antihypertensive effect of diuretics. Therefore, when ALDACTONE and NSAIDs are used concomitantly, monitor closely to determine if the desired effect of the diuretic is obtained [see Clinical Pharmacology (12.3)].
Spironolactone and its metabolites interfere with radioimmunoassays for digoxin and increase the apparent exposure to digoxin. It is unknown to what extent, if any, spironolactone may increase actual digoxin exposure. In patients taking concomitant digoxin, use an assay that does not interact with spironolactone.
Hyperkalemic metabolic acidosis has been reported in patients given ALDACTONE concurrently with cholestyramine.
7.6 Acetylsalicylic Acid
Acetylsalicylic acid may reduce the efficacy of spironolactone. Therefore, when ALDACTONE and acetylsalicylic acid are used concomitantly, ALDACTONE may need to be titrated to higher maintenance dose and the patient should be observed closely to determine if the desired effect is obtained [see Clinical Pharmacology (12.3)].